1. Field of the Invention
The present invention relates to a non-linear Hall IC for outputting voltage in accordance with a magnetic field strength, and more particularly, to a non-linear Hall IC having non-linear output characteristics.
2. Description of the Related Art
A Hall element is a semiconductor device for outputting voltage that is proportion to a magnetic field strength. A Hall IC comprising the Hall element combined with an amplifier circuit or correcting circuit has conventionally become commercially practical.
However, since the conventional Hall IC is formed for the sake of bringing the magnetic field strength and the output voltage into precise proportion to each other, although the conventional Hall IC is effective for measuring the magnetic field strength, it is necessary to prepare a calculating circuit for converting the output voltage into a desired value outside the Hall IC when it is unnecessary to bring the magnetic field strength and the output voltage into proportion to each other. Therefore, there are problems that an entire apparatus can not be reduced in size and costs thereof are increased.
For example, a shape of a fuel tank of an automobile is complicated and thus, a liquid level of fuel and an amount of fuel are not proportional to each other. Therefore, if an attempt is made to measure the amount of fuel by designating the displacement of liquid level with variation of magnetic field strength, and by measuring the magnetic field strength using the conventional linear Hall IC, although the liquid level can be measured precisely, the amount of fuel can not be measured precisely. Therefore, in the conventional Hall element, the calculating circuit is separately provided outside of the Hall IC to convert the output voltage of the Hall IC and to calculate the amount of fuel.
Since the calculating circuit is separately provided outside of the Hall IC in this manner, the Hall IC can not be reduced in size and costs thereof are increased.
The present invention has been accomplished in view of the above circumstances, and it is an object of the invention to provide a non-linear Hall IC capable of outputting arbitrary necessary output voltage to magnetic field strength.
To achieve the above object, according to a first aspect of the invention, there is provided a non-linear Hall IC for detecting a magnetic field strength using a Hall element to convert a Hall voltage outputted by the Hall element and output an output voltage, comprising storing means for storing conversion information for converting the Hall voltage outputted by the Hall element into the output voltage, and non-linear conversion means for converting the Hall voltage on a basis of the conversion information stored in the storing means thereby to establish a non-linear relation between the magnetic field strength and the output voltage.
According to the first aspect, it is possible to output arbitrary output voltage required for the magnetic field strength.
Therefore, if this non-linear Hall IC is utilized in a structure requiring non-linear characteristics such as the fuel tank for the automobile, since it is unnecessary to separately provide the calculation circuit, the entire apparatus can be reduced in size, and costs thereof can be reduced.
According to a second aspect of the invention, the conversion information stored in the storing means includes a plurality of sections of the magnetic field strength divided by arbitrary distances and the non-linear conversion means judges which of the sections the magnetic field strength corresponding to the Hall voltage does belong to and further converts the Hall voltage into the output voltage in each of the sections.
According to the second aspect, if this non-linear Hall IC is utilized in a structure requiring that characteristics are varied in each of arbitrary sections, since it is unnecessary to separately provide the calculation circuit, the entire apparatus can be reduced in size, and costs thereof can be reduced.
According to a third aspect of the invention, the conversion information stored in the storing means includes a plurality of sections of the magnetic field strength divided by constant distances and the non-linear conversion means judges which of the sections the magnetic field strength corresponding to the Hall voltage does belong to and further converts the Hall voltage into the output voltage in each of the sections.
According to the third aspect, if this non-linear Hall IC is utilized in a structure requiring that characteristics are varied in each of constant sections, since it is unnecessary to separately provide the calculation circuit, the entire apparatus can be reduced in size, and costs thereof can be reduced.
According to a fourth aspect of the invention, the non-linear conversion means establishes a curved relation between the magnetic field strength and the output voltage.
According to the fourth aspect, if this non-linear Hall IC is utilized in a structure in which characteristics are varied continuously, since it is unnecessary to separately provide the calculation circuit, the entire apparatus can be reduced in size, and costs thereof can be reduced.